A lift based Cycloidal Wave Energy Converter (CycWEC) was investigated using numerical simulations to estimate its mean annual power absorption. Based on the power absorption as well as size and ...weight estimates a number of performance measures were derived in order to compare this novel Wave Energy Converter (WEC) to other more established devices for which results have been published by Babarit et al. 1 using a similar benchmarking approach.
Comparison of these measures with published data for eight more established WEC designs, including heaving buoy, oscillating water column and flap devices shows that the CycWEC performance in all metrics exceeds that of all other devices. Most importantly, the energy per mass of the CycWEC exceeds that of all other devices by more than an order of magnitude, indicating the potential of the CycWEC to significantly lower the Levelized Cost of Energy (LCoE) and reducing it to a level where the CycWEC can compete with other renewable energy sources like solar and wind.
•Benchmarking of the novel Cycloidal Wave Energy Converter (CycWEC).•The CycWEC performance exceeds that of all other traditional WECs in every metric.•More than an order of magnitude improvement in cost of energy.•The CycWEC is expected to be cost competitive with established renewables like wind.
Noninvasive imaging at the molecular level is an emerging field in biomedical research. This paper introduces a new technology synergizing two leading imaging methodologies: positron emission ...tomography (PET) and magnetic resonance imaging (MRI). Although the value of PET lies in its high-sensitivity tracking of biomarkers in vivo, it lacks resolving morphology. MRI has lower sensitivity, but produces high soft-tissue contrast and provides spectroscopic information and functional MRI (fMRI). We have developed a three-dimensional animal PET scanner that is built into a 7-T MRI. Our evaluations show that both modalities preserve their functionality, even when operated isochronously. With this combined imaging system, we simultaneously acquired functional and morphological PET-MRI data from living mice. PET-MRI provides a powerful tool for studying biology and pathology in preclinical research and has great potential for clinical applications. Combining fMRI and spectroscopy with PET paves the way for a new perspective in molecular imaging.
The Problem of educational theory Siegel, Stefan T; Biesta, Gert
Policy futures in education,
06/2022, Letnik:
20, Številka:
Online First
Journal Article
Recenzirano
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This interview sheds light on current developments threatening the disciplinary ‘heart’ of education. Taking a starting point in the continental ‘configuration’ of the field, the authors argue that ...there are forms of theory considered distinctively educational. Based on this premise, they discuss why defining educational theories (Erziehungswissenschaftliche Theorien) is so challenging, and why it is nevertheless a rewarding endeavour. By distinguishing between (genuinely) educational theories in a narrow sense and (educationally relevant) theories in a wider sense, the authors attempt to tackle the problem of educational theory and to stimulate the discourse on theorizing education. (Verlag).
Erziehungswissenschaftliche Theorien sind ein konstitutives Element universitärer Pädagogikstudiengänge. Deshalb ist es von besonderem Interesse, was Studierende und Dozierende ...erziehungswissenschaftlicher und lehramtsbezogener Studiengänge über diese Theorien
denken, wie sie diese bewerten und inwiefern sie sich damit im Rahmen individueller Professionalisierungsprozesse auseinandersetzen. Zu diesen Fragen existieren bis dato nur wenige empirische Befunde.
The continuously forming fin bony rays of zebrafish represent a simple bone model system in which mineralization is temporally and spatially resolved. The mineralized collagen fibrils of the fin ...bones are identical in structure to those found in all known bone materials. We study the continuous mineralization process within the tissue by using synchrotron microbeam x-ray diffraction and small-angle scattering, combined with cryo-scanning electron microscopy. The former provides information on the mineral phase and the mineral particles size and shape, whereas the latter allows high-resolution imaging of native hydrated tissues. The integration of the two techniques demonstrates that new mineral is delivered and deposited as packages of amorphous calcium phosphate nanospheres, which transform into platelets of crystalline apatite within the collagen matrix.
Educational theories are a constitutive element of educational studies. Despite their theoretical relevance, little is still known about students’ and instructors’ understandings of educational ...theories and their theory-related attitudes and beliefs. ... To elucidate these constructs and to test their relevance, we conducted a mixed-methods study with 32 student sand 12 instructors of educational studies at a German university. ... We found that both groups perceived educational theories as rather abstract concepts. Students reported rather negative attitudes and naive beliefs. For both groups, we found that attitudes and beliefs were strongly tied to motivational and affective aspects when dealing with educational theories, which stresses their relevance for educational studies. ... We suggest a systematic theoretical clarification of the term educational theories. Furthermore, consideration of students’ and instructors’ theory-relatedattitudes and beliefs can give rise to meaningful practical implications (e.g., through self-reflection). (Orig.).
Research is often specialized and varies in its nature between disciplines, making it difficult to assess and compare the performance of individual researchers. Specific qualitative and quantitative ...indicators are usually complex and do not work equally well for different research fields. Therefore, the aim of the present study was to develop an economical questionnaire that is valid across disciplines. The authors constructed a Short Multidisciplinary Research Performance Questionnaire (SMRPQ), with which researchers can briefly report 11 quantitative and qualitative performance aspects from four areas ... in relation to their peer reference groups .... To validate this questionnaire, 557 German researchers from Physics, History, and Psychology fields ...completed it, and for the purpose of convergent and discriminant validation additionally made assessments regarding specific quantitative and qualitative indicators of research performance as well as affective, cognitive, and behavioural aspects of their research activities .... The results attested reliable measurement, endorsed the postulated structure of the newly developed instrument, and confirmed its invariance across the three disciplines. The SMRPQ and the validation measure were strongly positively correlated, and both demonstrated similar associations with affect, cognition, and behaviour at work. Therefore, it can be considered a valid and economical approach for assessing research performance of individual researchers across different disciplines, especially within nomothetic research .... (Orig.).
A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The ...detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm(3) and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and +/-5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when +/-10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing among multiple MPPC and to diffuse and direct scintillation light can reduce the nonlinearity of the detector response within the limited dynamic range of a typical MPPC. As a result, the proposed PET detector module has the potential to be refined for use in high-resolution PET insert applications.
Ocean waves offer an uninterrupted, rich resource of globally available renewable energy. However, because of their high cost and low power production, commercial wave energy converters are not ...operational at present. In this paper, we numerically evaluated the performance of a novel feedback-controlled lift-based cycloidal wave energy converter (CycWEC) at various sea states of the Humboldt Bay wave climate. The device comprised of two hydrofoils attached eccentrically to a shaft at a radius, submerged at a distance under the ocean surface. The pitch of the blades was feedback-controlled based on estimation of the incoming wave. The simulations were performed for regular waves and irregular waves approximated with a JONSWAP spectrum. Climate data from Humboldt Bay, CA was used to estimate the yearly power generation. The results underline the importance of a well-tuned control algorithm to maximize the annual energy production. The estimated annual energy production of the CycWEC was 3000MWh from regular wave simulations and 1800MWh from irregular wave simulations, showing that it can be a commercially viable means of electricity production from ocean waves.
A novel technique, called augmented whole-body scanning via magnifying PET (AWSM-PET), that improves the sensitivity and lesion detectability of a PET scanner for whole-body imaging is proposed and ...evaluated. A Siemens Biograph Vision PET/CT scanner equipped with one or two high-resolution panel-detectors was simulated to study the effectiveness of AWSM-PET technology. The detector panels are located immediately outside the scanner's axial field-of-view (FOV). A detector panel contains <inline-formula> <tex-math notation="LaTeX">{2} \times {8} </tex-math></inline-formula> detector modules each consisting of <inline-formula> <tex-math notation="LaTeX">{32} \times {64} </tex-math></inline-formula> LSO crystals (<inline-formula> <tex-math notation="LaTeX">{1.0} \times {1.0} \times {10.0} </tex-math></inline-formula> mm 3 each). A 22 Na point source was stepped across the scanner's FOV axially to measure sensitivity profiles at different locations. An elliptical torso phantom containing <inline-formula> <tex-math notation="LaTeX">7\times9 </tex-math></inline-formula> spherical lesions was imaged at different axial locations to mimic a multi-bed-position whole-body imaging protocol. Receiver operating characteristic (ROC) curves were analyzed to evaluate the improvement in lesion detectability by the AWSM-PET technology. Experimental validation was conducted using an existing flat-panel detector integrated with a Siemens Biograph 40 PET/CT scanner to image a torso phantom containing spherical lesions with diameters ranging from 3.3 to 11.4 mm. The contrast-recovery-coefficient (CRC) of the lesions was evaluated for the scanner with or without the AWSM-PET technology. Monte Carlo simulation shows 36%-42% improvement in system sensitivity by a dual-panel AWSM-PET device. The area under the ROC curve is 0.962 by a native scanner for the detection of 4 mm diameter lesions with 5:1 tumor-to-background activity concentration. It was improved to 0.977 and 0.991 with a single- and dual-panel AWSM-PET system, respectively. Experimental studies showed that the average CRC of 3.3 mm and 4.3 mm diameter tumors were improved from 2.8% and 4.2% to 7.9% and 11.0%, respectively, by a single-panel AWSM-PET device. With a high-sensitivity dual-panel device, the corresponding CRC can be further improved to 11.0% and 15.9%, respectively. The principle of the AWSM-PET technology has been developed and validated. Enhanced system sensitivity, CRC and tumor detectability were demonstrated by Monte Carlo simulations and imaging experiments. This technology may offer a cost-effective path to realize high-resolution whole-body PET imaging clinically.
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